Stock block??? Stop adding power immediately. Unless you want to have a very short lived thrill ride. I would go through Larrys tuning advice. Then I would read everything Larry has ever posted, then read all of Jim Weise posts, ounce you have all that info you can then take a step back and evaluate what you have. You probably have already gone too far for a stock block and before you read this may have already blown your motor. If you have gone to TA performance shop and talked to Mike T he may have already suggested to you to upgrade your oiling, and start with roller rockers. Im totally jealous that you live whiten driving distance of TA. That is like the holly grail of Buick performance. Its the Willy Wonka of chocolate factories, in comparison.
Chicken Little much??!?!? Oiling upgrades are certainly good, but you can go a ways over stock in the HP department if you are not winding the motor up to 6,000rpm every afternoon. Plus, if your bearing clearances are good (not too tight, not too loose), you don't need to run a crankcase full of 20w-50. Thinner oil works quite well, and get to all the places that need lubrication quickly, just manage the thickness for minimum oil pressures. I run a 50/50 mix of 20w-50 and 10w-30 in the summer and straight 10w-30 in the winter to keep my running pressures happy. ~20psi at 800rpm idle and 50psi at 2,400rpm cruising speed, and it winds out around 70psi by 5,000rpm. You're in a bit of a warmer climate than I, so your mileage may vary a bit. I've never spun a bearing in any of my 455's (hammered a few from lacking octane, but never spun). The T/A timing cover is a nice piece to have at some point and I recommend the iron wear plate (not to be confused with a HV kit).
Headers, 850 Holley carb, TA SP1 intake would be a great start. Your 750 is smaller than the Quadrajet that came on it from factory.
HEADERS DO NOT FIT 1965-67 A BODY...........unless you smash the tubes in on both sides or go STAGE 2. TA Stage 2 heads and headers will fit easily without use of a big f...... hammer. I would go this way and skip porting iron heads. Consider all the good advice in this thread and start by doing this right now. 1. Curve that distributor and set a maximum mechanical timing at about 32-34. 2. Make sure you have an exhaust system that can breath. Headers offer almost no horsepower until you blow over 400 HP down those pipes. 3. Cam selection... you may want a cam that has good enough manners and does NOT require notched pistons and roller rockers $$$ Here are three simple drop-in cams. Remember, stock pistons and rockers are ok with these cams. A. TA C118- very good idle but has good power. An old favorite street/strip cam. Works great with stock exhaust manifolds. Mid 12's in the 1/4 mile. B. TA 288-94 - good idle with a mild chop, and about 5-10 more hp than the c118. Good with stock exhaust or headers. BUQUICK runs 12. teens with this cam and iron manifolds, MT 235/60R-15 tires. Sock appearing 4000 lb. convertible. C. TA 310 - choppy idle but manageable on the street. Power brakes still work. Buickrat1 runs low 11's with iron exhausts with this cam!!!!but headers would definitely help. 4. Starting at the rear and working forward is good advice. You need traction first. Gears...well 3.08 to 3.73 range is fine. Use 26" MT radial with 3.08 and you'll have plenty of fun. Lower gears and higher stall converters just require more work on getting traction, and eventually you'll get to that part as the power increases. Start with soft springs on front (Moog 6204) and MT 235/60R-15 drag radials on back. They are small, but killer traction without major clearance problems.
When I put headers on my 66 Special I notched the frame where they hit. They were 2" Kenne Bell headers but should be close to the same shape as TA. I welded steel pieces in where I notched it but as strong as that area is it shouldn't matter if you add those pieces or not. I have the right side notched on my Regal and just left it but the 307 olds won't ever hurt it. I will post a pic of the Regal frame if I find it. I never dent my headers I alway move the obstacles in the way.
